The present invention relates to testing of a low power radio frequency (RF) data packet signal transceiver, and in particular, to testing such a device using data packets exchanged between a tester and the device as a normal part of a communication link initiation sequence.
Many of today's electronic devices use wireless signal technologies for both connectivity and communications purposes. Because wireless devices transmit and receive electromagnetic energy, and because two or more wireless devices have the potential of interfering with the operations of one another by virtue of their signal frequencies and power spectral densities, these devices and their wireless signal technologies must adhere to various wireless signal technology standard specifications.
When designing such wireless devices, engineers take extra care to ensure that such devices will meet or exceed each of their included wireless signal technology prescribed standard-based specifications. Furthermore, when these devices are later being manufactured in quantity, they are tested to ensure that manufacturing defects will not cause improper operation, including their adherence to the included wireless signal technology standard-based specifications.
For testing these devices following their manufacture and assembly, current wireless device test systems typically employ testing subsystems for providing test signals to each device under test (DUT) and analyzing signals received from each DUT. Some subsystems (often referred to as “testers”) include one or more vector signal generators (VSG) for providing the source, or test, signals to be transmitted to the DUT, and one or more vector signal analyzers (VSA) for analyzing signals produced by the DUT. The production of test signals by a VSG and signal analysis performed by a VSA are generally programmable (e.g., through use of an internal programmable controller or an external programmable controller such as a personal computer) so as to allow each to be used for testing a variety of devices for adherence to a variety of wireless signal technology standards with differing frequency ranges, bandwidths and signal modulation characteristics.
Testing of wireless devices typically involves testing of their receiving and transmitting subsystems. The tester will typically send a prescribed sequence of test data packet signals to a DUT, e.g., using different frequencies, power levels, and/or modulation technologies, to determine if the DUT receiving subsystem is operating properly. Similarly, the DUT will send test data packet signals at a variety of frequencies, power levels, and/or modulation technologies to determine if the DUT transmitting subsystem is operating properly.
Low power RF data packet signal transceivers often exchange data packets as a part of a sequence to initiate a communication link. One example is a personal area network (PAN) technology known as Bluetooth Low Energy (BLE, or also known as “Bluetooth Smart”), which is designed to be very conservative in its energy requirements while providing connectivity between a central device (“client”) and a peripheral device (“server”) once a connection is established. Examples of such devices include a “smartphone” as a central device and a pulse-rate sensor connected to a user's wrist as a peripheral device.
The original Bluetooth devices were designed to provide wireless data connections for mobile applications such as on-air headsets to cellphones and portable speakers to MP3 playback devices. The newer BLE devices are designed to be simpler and to convey data in smaller quantities and at lower speeds to minimize power use, thereby preserving battery life and enabling operation over extended periods of time.
During manufacturing, when a BLE subsystem is being tested, an input/output (I/O) port is available to facilitate conductive testing of receiver and transmitter physical-level behavior as well as DUT control. However, once the BLE subsystem is combined with the server peripheral device (e.g., a sensor), the I/O port is typically no longer available (e.g., removed or encapsulated). Hence, testing at that stage must be performed wirelessly using radiative signaling (e.g., via wireless RF signals). However, since separate DUT control is rarely available (e.g., neither a conductive signal path nor a wireless control signal channel is available), such testing relies upon establishing a wireless communication link between a tester and the BLE-based peripheral device-under-test (DUT), with DUT control established by including driver software within the DUT and DUT-specific testing software within the tester. Such requirements for driver and testing software increase testing complexity and time and thereby increase testing costs.
Additionally, continuing with the BLE example, the data packets used by a peripheral device to initiate a communication link can be transmitted on any of multiple (e.g., three) channels in random order. Unless a testing system knows in advance on which channel the DUT will transmit, it cannot deterministically transmit a responsive data packet on that same channel. This can significantly delay test time, or require some form of predetermined coding to be employed within the DUT, which would negate the use of a generalized testing methodology.
Further with the BLE example, pending establishment of a communication link, a relatively long time interval exists between data packet sequences seeking to initiate a communication link. Meanwhile, during the link initiation sequence, initiating data packets are transmitted on the multiple prescribed channels in rapid succession. It would be advantageous if such rapid sequence of data packets could be used for testing, and thereby derive more test data, faster, and reduce overall test time.